Synthetic lubricants



Patented Mar. 14, 1950 SYNTHETIC LUBRICANTS Orland M. Reifi', Harry J.Andress, Jr., and Alfred P. Kozacik, Woodbury, N. J., assignors toSocony-Vacuum Oil Company, Incorporated, a corporation of New York NoDrawing. Application May 11, 1949, Serial No. 92,744

17 Claims. I

This invention has to do with synthetic lubricants and with a processfor their preparation. More particularly, this invention concerns acatalytic condensation of certain mono-olefins and styrene whereby lowpour point lubricants are formed.

As is well known in the art, plastic compositions have been formed bycopolymerization of unsaturated hydrocarbons with styrene. For example,copolymerization has been efiected at low temperatures in the presenceof active catalysts typified by boron trifiuoride. Under such conditionsas these high molecular weight, linear copolymers are formed. As shownin U. S. Letters Patent 2,274,749 these copolymers are viscosity indeximproving agents when incorporated, in small amounts, in mineral oils.Copolymers of a similar character have also been obtained by reaction ofunsaturated hydrocarbons with styrene polymers (polystyrol) in thepresence of clays impregnated with hydrogen fluoride or borontrifluoride (U. S. Letters Patent 2,282,456).

In co-pending application Serial No. 6,993, filed February 7, 1948, byF. M. Seger and A. N. Sachanen, a non-catalytic process for thepreparation of synthetic lubricants is described. This noncatalyticprocess involves condensation of a straight-chain, normal alphamono-olefin of five to twelve carbon atoms. with styrene at atemperature from about 500 F. to about 700 F. The lubricants obtained bythis process are of excellent character, with low pour points, highviscosity indices and good stability. Unfortunately, however,condensation or copolymerization is generally incomplete and thesynthetic lubricants contain polystyrenes. as evidenced by relativelyhigh cloud points (+60 F.).

It has now been discovered that synthetic lubricants free from theundesirably high cloud points of the foregoing lubricants are obtainedby a catalytic condensation of mono-olefins and styrene. The newlubricants have very low pour points, excellent stability and have aconsiderable range of viscosities. In sharp contrast with the copolymersreferred to above in connection with 2,274,749 and 2,282,456, theproducts obtained by the present process do not behave as viscosityindex improving agents when incorporated in mineral oils. The productsformed in the present process have molecular weights of the order of 300to 500, generally 340 to 470.

Reactamts The mono-olefins of this invention contain from eight toeighteen carbon atoms.

Illustrative of such olefins are: octenes such as octene-l and octene-2,nonenes as nonene-l, decenes such as decene-l, dodecene-l, hexadecene-l,octadecene- 1, and the like. Preferred of such olefins, however, are thenormal, alpha mono-olefins of ten to eighteen carbon atoms, particularlydecene-l, dodecene-l, tetradecene-l, hexadecene-l, and octadecene1 forsuch olefins form outstanding synthetic lubricants with styrene and itshomologs.

Not only may the mono-olefins of the aforesaid character be usedindividually in this invention, but they may also be used in admixturewith each other. Here again, however, mixtures containing a majorproportion of one or more normal, alpha mdno-oleflns (or normall-oleflns) are preferred. Representative mixtures are those obtained bythe cracking of paraffin waxes and other parailin products, and thoseobtained from the Fischer-Tropsch and related processes. The hydrocarbonmixtures may contain, in addition to the desired olefins, such materialsas: other olefins, paraffins, naphthenes and aromatics.

As indicated above, styrene is condensed or copolymerized with theforegoing mono-olefins. In addition to styrene, however, homologs andderivatives of styrene may also be used. For example, alpha-methylstyrene has been found to form excellent synthetic lubricants in thepresent process. Other styrene derivatives include: pchlorostyrene,p-methoxystyrene, p-alkylstyrenes as p-methylstyrene, etc. 'Thesubstituent group or groups, such as chloro in p-chlorostyrene,generally modifies the character of the oil products, yet, in all cases,the products are characterized by desirably low pour points and areuseful as lubricants. By way of illustration, when pchlorostyrene isused, the synthetic lubricant formed possesses a high degree of filmstren th. Similarly, a fiuoro-substituted styrene imparts additionalstability to the synthetic lubricant product as well as film strength orextreme pressure properties. As will be noted from the character of theforegoing typical substituted styrenes,

substituent groups which may be present are those which do not interferewith the condensation or copolymerization with the mono-olefin. In otherwords, a substituent group which may be present in the styrene is onewhich is substantially inert or unreactive in the condensation.

Similarly, vinyl-substituted polynuclear compounds may also be used inplace of, or in comhination with, styrene and the latters homologs andderivatives. Representative vinyl-substituted polynuclear compounds arevinylnaphthalene.

a,soo,aos

chloro vinylnaphthalene, vinylanthracene and the like.

It will be understood, of course, that mixtures of the aforesaid vinylaromatic compounds, and their aforesaid derivatives, may be used inplace of the individual reactant. Similarly, mixtures containingsubstantial, preferably major, proportions of one or more of said vinylcompounds may be used. Examples of such mixtures include: a crudestyrene containing ethylbenzene, divinyl benzene and ethyl styrene.

Preferred of the vinyl aromatic compounds, in view of the outstandingcharacter of the lubricants obtained therewith, is styrene.

Catalysts The catalysts operative in the present process are porous,absorptive associations of silica and various amphoteric metal oxides,and particularly those of alumina, thoria andzirconia. They may beclassified, for example, as active clay, and synthetic alumina-silica,thoria-silica and zirconia-silica catalysts. Preferred of thesesynthetic catalysts are those which contain an excess of silica withsmaller amounts of alumina, thoria and zirconia; and which may or maynot contain not more than one per cent of a third metal or metal oxide,with the exception of alkalies or alkaline earths which should not bepresent in amounts greater than approximately 0.1 per cent. The activeclay catalysts should conform to these same specifications, except thatthey should contain not more than ten per cent of the oxides of calcium,magnesium and iron, not more than three per cent of said oxides beingiron oxides. The amount of silica will generally vary from about '70 to80 per cent and the amount of alumina for example, will vary from aboutto per cent by weight of the catalyst.

Illustrative catalysts are naturally -occurring silica-alumina clays ofthe montmorillonite type, fullers earth, Attapulgus clay; syntheticporous absorptive composites comprising silica and alumina which may beformed in various ways, as for example, precipitating silica on alumina,or alumina on silica, or by combining a silica gel with alumina or bypreparing a silica-alumina gel.

Synthetic silica-alumina catalysts may be prepared in numerous ways wellknown to the art by the formation of gels or gelatinous precipitatescomprising essentially silica and alumina. A representative method ofpreparing such catalysts is described in U. S. Letters Patent 2,232,727,issued to Peterkin et al. Other particularly efiective catalysts arespheroidal pellets of silicaalumina gel, prepared by mixing an acidicstream of aluminum sulphate and a stream of sodium silicate, andallowing the resulting sol to be ejected from a nozzle into an oilcolumn where the gel sets in the form of bead-like pellets. Theresulting gel spheresafter washing, drying and tempering-were found tobe excellent catalysts in the present process. A further description ofthe method for preparing the above-described spheroidal pellets isdisclosed in U. S. Letters Patent 2,384,946, issued September 18, 1945to Milton M. Marisic.

The catalyst, whether a natural clay or a synthetic composite, shouldpreferably have a fairly small particle size. After use in thecondensation herein, the spent catalyst may be reactivated at elevatedtemperatures for a period sufficient to restore its original activity.Thus, a spent silica-alumina catalyst may be reactivated by 4 heating atabout 1000 F. for about two hours. The original catalyst may thereforebe reused a considerable number of times before it degeneratescompletely and must be discarded.

Reaction conditions Copolymerization of the aforesaid reactants iseffected at elevated temperatures. It appears that temperatures as lowas 300 F. and as high as 600 F. may be used. At temperatures from 300 F.to 400 F., however, reaction rate is slow; and, at temperatures above600 F., undesirable side reactions, such as cracking, take placeresulting in lower yields of oils of high flash point. Preferredoperating temperatures, therefore, range from 400 F. to 500 F.

Condensation is generally complete in from four to ten hours, preferablyfour to seven hours, with the higher reaction temperatures being usedfor the shorter reaction periods and with the lower reactiontemperatures being used for the longer reaction periods.

Pressures ranging from atmospheric to about 300 pounds per square inchcharacterize the proc ess. In general, it is desirable to use suflicientpressure to maintain the reactants in liquid state.

Proportions of reactants can be varied considerably to form productssuitable for different uses. With equimolar proportions of mono-olefinand styrene, the products are principally of the copolymer type asevidenced by a low degree of unsaturation. A higher proportion of themonoolefin than that corresponding to a 1:1 molar ratio, providesproducts of higher viscosity index (V. I.), lower viscosity and lowerpour point, which products are considered to be mixtures of polymerizedmono-olefins and copolymers. In general, therefore, the molar proportionof monoolefin to vinyl aromatic compound, such as styrene, will rangefrom 1:1 to 2:1, preferably about 1:1.

It will be understood that the condensation is aided by providing mixingof the reactants. This may be provided by using various agitating meanswhich are well known in the art. At the reaction conditions, thereactants are readily soluble and homogeneity is easily obtained.

Examples In order to illustrate the principles of this invention, theresults of a series of typical, and nonlimiting, condensations are setforth in tabular form in Table I below. These condensations, with theexception of run 16, were carried out in a rocking-type bomb (AmericanInstrument Co.). The reactants and catalyst were charged to the bomb,which was then heated to the desired temperature for the desired lengthof time. Thereafter, the bomb was cooled and discharged. The contents ofthe bomb were suction-filtered in order to remove catalyst, and thefiltrate was vacuum distilled to remove any unreacted materials andproducts of intermediate boiling range. To distinguish the condensationproducts from the distillate fractions, the refined oils are identifledas residual oils. The latter term identifies the oils from whichunreacted materials and products of intermediate boiling range have beenseparated.

In the case of run it, an autoclave equipped with a stirrer was usedrather than a rocking-type bomb.

It should be noted that the reaction times. recited as time, hours" inTable I, represent the time intervals during which the bomb or autoclaveand its contents was maintained at the of a synthetic silica-aluminacatalyst formed by pelleting (analysis: 87.5% silica, 12.5% alumina),was charged to a stainless steel, rocking-type bomb. After the bomb headwas secure, approxdesired temperature, and do not include the timeimately 1,800 pounds per square inch of nitrointervals necessary to heatthe reaction vessel gen was pressured into the bomb to check for and itscontents to the desired temperature, and leaks. The pressure was thenreleased, the system also do not include the time intervals necessarywas again closed and the bomb was heated to to cool and/or discharge thereaction vessel after 500 F. in the course of six hours and held at thatheat to the vessel has been discontinued. As a temperature for sixhours. During the reaction, guide, however, about three hours weregenerally a pressure of 150 pounds per square inch develrequired to heatthe bomb from about 70 F. to oped. After cooling the bomb to roomtempera- 500 F., and about four hours were required to ture (70 F.),during a period of four hours, the cool the bomb from 500 F. to 70 F.and to disreactionf'product was discharged into a vessel and charge thebomb. l5 diluted with benzene. The benzene-diluted Styrene used in thesecondensations contained product was then suction filtered to remove thea fraction of one per cent of p-tertiary-butylcate catalyst. Benzene wasremoved from the filtrate chol. the latter acting as a stabilizer orpolymeriby distilling the latter at atmospheric pressure zationinhibitor. This styrene material is a comto a maximum temperature of 125C. The benmercial product now available. zene-free product was thenvacuum distilled, By way of illustration, the procedure followed invacuum of 5 mms. of Hg, to a liquidtemperature run 4 of Table I, below,is provided in detail. A of 100 C., whereupon any unreacted material andmixture of 208 parts by weight (2 molar proporproducts of intermediateboiling range were retions) of styrene, 224 parts 'by weight (2 molar Mmoved. The residual oil, 231.5 parts by weight,

proportions) of octene-l and 43 parts by weight falls within thelubricating oil range.

Table I Reactants Reaction Conditions 1 P 1 P 1 P t l 0. 81' S 1- :11 5ar S hnyl Aromatic Temp. Time Olefin by Moles by Moles Catalyst 1)Weight COmPOWd Weigh weight Pentcne-2 223 3. 2 300 2. 9 Synthetic 13,AlurninaSilica. 52 400 6% Pentenes 202 2.8 300 2.9 -..do 50 400 6Octane-1 224 2.0 208 2.0 r, Di-isobutylenc 224 2.0 208 2. 0 6 Dodecene-1164 0.98 104 1.0 6%

do 104 0. 02 re 0.5 4

Unsaturated Kero- 250 1.3 4.3 0.4 7

sene

lo 250 1.3 21.5 0.2 Hexadecene-l 224 1. 0 104 1. 0 5 Octadeeene-l 126 0.5 52 0. 5 5;;

Octadecene 1 103 1]. 4 42. 5 0.4 5 Octadecene-l 252 1.0 104 1.0 5Unsaturated Wax D. 206 0. 95 92 0. 88 6 Residual oil Run 1 N2 Max.Press. Parts by Weight Per- 13 f? 533; K. v. K. v V I 0101141 Iodine A.P. 1. (p. s. i.) Weight Cent Yield Weight 0 R 100 F., Cs. 210 F Cs.Point, F No. Gravity 307 58.7 1231030 1 95.45 273 54.1 469 143 20. 3 342585.8 13. 47 231 53. 5 -10 329. 3 13. s 284 05. 7 -5 140. 1 0. 05 20576.2 -20 142. 7 11.74 10s 76. 1 421 -30 107. 1 10. 121 41.3 10 321.314.18 100 35. s -15 141.1 10.31 257 72. 0 -20 27. 32 4. 97 154 so. 5 1o40. 22 7.08 116 76.3 15 67.69 9.54 188 50.8 s 23. 95 4.04 102 70. 1 3660 70. 1s 9. 53 32s 91. 5 397 15 5s 7. 59 320 29. 3 423 01. 3 s. 309 68.4 370 7 90. s 11. 48

Notes on Table I: A=A mixture of pentenes, boilmg range, 32 C. to 60 C.

B=A synthetic alumina-silica catalyst formed by pelleting. andcomprising approximately 12.5 per cent alumina and 87.5 per cent silica.C=An unsaturated kerosene fraction having an iodine number of 42 and :maverage carbon chain length of 14: prepared by dchydrohalogenation of aehlorokerosenc of 17.6 per cent chlorine content.

D=An unsaturated para iin Wa having an iodine nu'nbcr of 3 and anaverage carbon chain length 0120: prcgnrczl by dchydrolmbgenatlon of nchlorowax of 14 per cent chlorine content.

E=An unsaturated paraflin wax having an iodine number of 152 and anavenge of chlorowax of 20 per cent chlorine content.

carbon chain length of 20; prepared by dehydrohalogenation F=Isomerizedoctadeccnel free from the latter olefin, having 11 bromine number 0163.1and a refractive inder of 1.4460 (11 G=Oalculated from correspondingbromine number of 9.1.

H=Syntl1etic alumina-silica catalyst in finely divided form andcontaining approximately ten per cent alumina. and ninety per centsilica.

A number of observations may be made from the data set forth in Table I,above. Runs l-3 reveal that oils obtained with pentenes have relativelyhigh pour points and have low viscosity indices. The chain length of themono-oleflns, pentenes, is believed to be inadequate. Similarly, runs 16and 17 demonstrate that high pour point oils are obtained whenmono-oleflns of twenty carbon chain length are used, evidence that thecarbon chain is excessively long. In contrast are runs 4-15 whichillustrate the present invention. In the latter runs, the oils obtainedare of low pour point, from +15" F. to 30 F.

Runs 4-5 reveal that low pour point oils are obtained with octenes asthe mono-olefin reactant, and also reveal that such oils have lowviscosity indices. These oils are well suited for applications whereinlow pour point is essential and wherein viscosity index is ofnoconsequence. For example, these oils may be used as blending stocksfor other oils.

The oils obtained from dodecene-l in runs 6 and 7 illustrate thedifference in properties which may be realized by varying the mol ratioof dodecene-l and styrene. When less styrene is used (run 7), the 011product formed has a higher viscosity index and a lower pour point.

Runs 8 and 9 were made with oleflns having an average carbon chainlength of fourteen. These olefins are mixtures with the double bond inalpha, beta or gamma position, and with some cyclopara-fiin nucleipresent. It is considered that the relatively low viscosity indices ofthe oil products may be attributed to the complexity of the olefins,rather than to their carbon chain lengths. With an individual olefin ofthe same chain length, particularly a normal, alpha mono-olefin, theoils formed therefrom would be characterized by considerably higherviscosity indices. It is to be noted from runs 8 and 9, however, that V.I. is higher when higher molar proportion of olefin to styrene than 1:1is used.

Hexadecene-l is the mono-olefin reactant of run 10, offering acomparison with octene-i of run 4 and with dodecene-l of run 6. Whilethere is no great difi'erence in the pour points of the oils obtainedwith these three olefins, there is a considerable difference in V. I.,with the oil obtained from hexadecene-l being outstanding.

Runs 11-15 involve octadecenes and serve to illustrate severalrelationships. Run 11 with octadecene-1 and run 14 with isomers of thisolefin reveal that an oil of somewhat lower pour point is obtained witha non-l-olefln though such an oil is characterized by a lower V. I. Runs12 and 13 show that an oil of somewhat lower pour point is obtained withalpha-methyl styrene than with styrene; however, styrene is considerablymore reactive and a higher yield is realized than with the methylderivative. Runs 11 and 15 indicate that the catalyst pellets and beadfines are of about the same order of effectiveness.

As indicated hereinabove, the residual oils of this invention do notbehave as viscosity index (V. I.) improving agents for lubricating ofls,in contrast to products obtained by copolymerizing unsaturatedhydrocarbons with styrene in the presence of boron trifiuoride and thelike. The behavior of several representative residual oils, incorporatedin a mineral lubricating oil in relatively low concentration, isprovided in Table II below. By way of comparison, two representativecommercial V. I. agents in typical lubricants are also shown in TableII.

Table II Kinematic Conc., Viscosity Residual Oil, Run Percent, v I C cNo. in Minin V.

era! Oil 100 F., 210 F.,

cs. cs.

30. 37 4. 79 76. 9 7 32. 13 4. 69 79. 4 Z. I 14 5 31.07 4. 89 81. 3 4 l55 31. 82 4. 93 79. 0 2. 1

48. 73 6.16 72. 5 X l 67. 89 8. 30 99. 5 +27. 0 Y l 61. 1 7. 90 103. 2+117 x 1 14s. 2 14. as 107 +5 35. 5 5. 70 110. 2 X l 48. 17 7. 43 122. 8l2. 6 Y l 43. 22 7. 10 129. 1 l8. 0

X and Y are commercial viscosity index agents.

As will be evident from the data presented above in Table I, thecondensation products 01' this invention are highly desirable lubricantsper se. They are also of considerable value as blending agents for otherlubricating oils. Typical oils with which the synthetic oils may beblended are mineral oils such as are normally used in internalcombustion and turbine engines. When so blended, the synthetic oils maycomprise the major proportion of the final blended oil, or may evencomprise a minor proportion thereof.

One or more of the individual properties or the synthetic lubricants ofthis invention may be further improved by incorporating therewith asmall, but efiective amount, of an addition agent such as anantioxidant, a detergent, an extreme pressure agent, a foam suppressor,a viscosity index (V. I.) improver, etc. Antioxidants are well-known inthe art, and are generally characterized by phosphorus, sulfur,nitrogen, etc. content; representative of such materials is anoil-soluble, phosphorusand sulfur-containing reaction product of pineneand phosphorus pentasulfide. Typical detergents which may be so used aremetal salts of alkyl-substituted aromatic sulfonic or carboxylic acids,as illustrated by diwax benzene barium sulfonate and barium phenate,barium salt of a wax-substituted phenol 5o carboxylic acid. Extremepressure agents are well known; illustrating such materials are numerouschlorine and/or sulfur containing compositions, one such material beinga chlornaphtha xanthate. Silicones, such as dimethyl silicone, may beused to illustrate foam suppressing compositions. Viscosity indeximproving agents which may be used are typified by polypropylenes,polyisobutylenes, polyacrylate esters, and the like.

contemplated also as within the scope of this invention is a method oflubricating relatively moving surfaces by maintaining therebetween afilm consisting of any of the aforesaid oils.

It is to be understood that the foregoing de- 55 scription andrepresentative examples are nonlimiting and serve to illustrate theinvention,

which is to be broadly construed in the light of the language of theappended claims.

We claim:

1. The method of preparation of a viscous oil having a low pour pointand a low cloud point, which comprises: heating a charge consistingessentially of a mono-olefin having between about eight and abouteighteen carbon atoms per molecule and a vinyl aromatic compound, in thepresence of a catalyst comprising an association oi silica and anamphoteric metal oxide, at a temperature between about 300 F. andabout600 F. for a period of time sufiicient to eflect condensation ofsaid mono-olefin and said vinyl aromatic compound, the charge containingfrom about one to about two molar proportions of said mono-olefin permolar proportion of said vinyl aromatic compound.

2. The method of claim 1 wherein the temperature is between about 400 F.and about 500 F. p

3. The method of claim 1 wherein the monoolefln contains between aboutten and about eighteen carbon atoms per molecule.

4. The method of claim 1 wherein the monoolefin is a normal, alphamono-olefin.

5. The method of claim 1 wherein the vinyl aromatic compound is amono-vinyl benzene.

6. The method of claim 1 wherein the catalyst is a porous absorptiveactivated silica-alumina clay.

7. The method of claim 1 wherein the catalyst is a porous absorptivesynthetic silica-alumina composite.

8. An oil of lubricating viscosity having a low pour point and a lowcloud point, and obtained: by heating a charge consisting essentially ofa mono-olefin having between about eight and about eighteen carbon atomsper molecule and a vinyl aromatic compound, in the presence of acatalyst comprising an association of silica and an amphoteric metaloxide, at a temperature between about 300" F. and about 600 F. for aperiod of time suflicient to eflect condensation of said mono-olefin andsaid vinyl aromatic compound, the charge containing from about one toabout two molar proportions of said mono-olefin per molar proportion ofsaid vinyl aromatic compound.

9. The oil of claim 8 wherein the temperature is between about 400 F.and about 500 F.

10. The oil of claim 8 wherein the mono-olefin contains between aboutten and about eighteen carbon atoms per molecule.

11. The oil of claim 8 wherein the mono-olefin is a normal, alphamono-olefin.

12. The oil of claim 8 wherein the vinyl aromatic compound is amono-vinyl benzene.

13. The oil of claim 8 wherein the catalyst is a porous absorptiveactivated silica-alumina clay.

14. The oil of claim 8 wherein the catalyst is a porous absorptivesynthetic silica-alumina composite.

15. An oil of lubricating viscosity having a low pour point and a lowcloud point, and obtained by: heating a charge consisting essentially ofn-dodecene-l and styrene in substantially equimolar proportions, in thepresence of a porous absorptive synthetic silica-alumina compositecomprising about 87.5 per cent silica and about 12.5 per cent alumina,at about 500 F. for about seven hours.

16. An oil of lubricating viscosity having a low pour point and a lowcloud point, and obtained by: heating a charge consisting essentially ofn-hexadecene-1 and styrene in substantially equimolar proportions, inthe presence of a porous absorptive synthetic silica-alumina compositecomprising about 87.5 per cent silica and about 12.5 per cent alumina,at about 500 F. for about flve hours.

17. An oil of lubricating viscosity having a low pour point and a lowcloud point, and obtained by: heating a charge consisting essentially ofn-octadecene-l and alpha-methyl styrene in substantially equimolarproportions, in the presence of a porous absorptive syntheticsilica-alumina composite comprising about 87.5 per cent silica and about12.5 per cent alumina. at about 500 F. for about six hours.

ORLAND M. REIFF.

HARRY J. ANDRESS, JR. ALFRED P. KOZACIK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,368,110 Buell Jan. 30, 19452,401,865 Gorin et a1 June 11, 1946 2,442,644 Elwell et a1 June 1, 19482,474,881 Young et al. July 5, 1949

1. THE METHOD OF PREPARATION OF A VISCOUS OIL HAVING A LOW POUR POINTAND A LOW CLOUD POINT, WHICH COMPRISES: HEATING A CHARGE CONSISTINGESSENTIALLY OF A MONO-OLEFIN HAVING BETWEEN ABOUT EIGHT AND ABOUTEIGHTEEN CARBON ATOMS PER MOLECULE AND A VINYL AROMATIC COMPOUND, IN THEPRESENCE OF A CATALYST COMPRISING AN ASSOCIATION OF SILICA AND ANAMPHOTERIC METAL OXIDE, AT A TEMPERATURE BETWEEN ABOUT 300*F. AND ABOUT600* F. FOR A PERIOD OF TIME SUFFICIENT TO EFFECT CONDENSATION OF SAIDMONO-OLEFIN AND SAID VINYL AROMATIC COMPOUND, THE CHARGE CONTAINING FROMABOUT ONE TO ABOUT TWO MOLAR PROPORTIONS OF SAID MONO-OLEFIN PER MOLARPROPORTION OF SAID VINYL AROMATIC COMPOUND.